1. Field of the Invention
The present invention relates to a device for spectacles for measuring eye points of a subject with respect to a spectacle frame.
2. Description of Related Art
In adjusting spectacles, it is important to measure eye points, such as the sighting position (visual line position) of a customer (hereinafter referred to as a subject) with respect to a spectacle frame selected by the subject and the pupillary distance.
Conventionally, for the measurement of the eye points, methods such as a method of marking the sighting position (visual line position) of the subject on spectacle lenses with a marker pen by the inspector with the subject sighting horizontally, and a method of attaching an eye point marking sticker at the position of the sight by confirming the near sighting position (visual line position) and the position of the pupils at a short distance (so-called mirror method) have been executed.
Moreover, for obtaining the inter-pupillary center distance (hereinafter referred to as PD),a pupillary distance measuring device has been used (see U.S. Pat. No. 4,944,585). Further, the PD has been measured by an eye refractive power measuring apparatus for automatically measuring the refractive power of an eye (see U.S. Pat. No 5,764,341).
Furthermore, an apparatus for photographing the face of a subject with a spectacle frame on by a television camera for finding the eye points by the photographed image (see JP-A-9-145324) has been proposed.
However, since the method of marking with a marker pen and the method of attaching a sticker executed according to observation of the sighting state of the subject by the inspector, it is highly dependent on the positional relationship between the subject and the inspector, and the experience of the inspector, and thus it is liable to be inaccurate. Moreover, these methods requires much time in measurement.
Further, since the PD obtained by the pupillary distance measuring device or the eye refractive power measuring apparatus is utilized for adjusting spectacles without examining the position with respect to the spectacle frame, it is liable that the pupillary center and the optical center of the produced spectacles do not coincide. Moreover, although the pupillary distance measuring device is fixed to the face of the subject by a nose contact member, since the nose shapes of subjects vary, an error can easily be generated depending on the contacting state.
Furthermore, the apparatus for finding the eye points from the photographed image by the television camera requires a complicated apparatus configuration, and thus a problem of a high cost is involved. Moreover, since the apparatus is the objective type, it is disadvantageous in that whether or not the measured position is correct cannot be confirmed by the subject himself. Further, according to the apparatus, since the face of the subject is photographed by the television camera in a fixed state, the measured eye position can be inaccurate depending on the difference of the targeted distance of sight in use by the subjects.
Furthermore, recently, progressive (progressive multi-focus) lenses have been demanded increasingly. In the case of a progressive lens, positioning with respect to the eyes is particularly important compared with the case of a single focus lens. That is, it is necessary to measure the eye points for the far vision and the near vision further accurately for a progressive lens, depending on the subject's environment of use. However, the eye points for the far vision and the near vision in a progressive lens cannot be measured accurately according to conventional methods and apparatus. Moreover, the subject cannot learn easily how the optical pattern distribution of the progressive lenses with different styles provided by different manufacturers can influence his vision in relation to the position of the eye points.